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.� ' Architecture <br /> Engineering An Employee-Owned Company <br /> Environ menta I Stormwater Management Report <br /> . Land Surveying <br /> Companies <br /> Existing Hydrologic Conditions <br /> The area included in the hydrologic analysis consists of approximately 9.06 acres, or 394,652 <br /> square feet. This area contains the project developments, including the warehouse building, <br /> parking lot,associated driveways, and landscaped areas.Previously,the area was undisturbed. The <br /> resident soil group is a mix of Group C &D soils. A breakdown of the Pre-Development Area and <br /> the Determination of Volume is shown below on Table 1. As this project is a new development, a <br /> storm volume of 0.51 inches was used for volume reduction requirements. <br /> Table 1 —Determination of Pre-Develo ment(Existing Conditions Volume <br /> Element Weighted 0.51-inch <br /> Site Element Area Percent of Runoff Runoff Storm <br /> (ft') Total Area Coeffection Coefficient Volume, <br /> (Cr) (Cra) ft3 <br /> Disturbed Soils: 394,652 1.00 0.05 1.0 x 0.05 <br /> GroupC/D Soil = 0.05 <br /> Total 394,652 0.05 839 <br /> The completed San Joaquin County Calculation spreadsheets can be found in Appendix E. <br /> Proposed Hydrologic Conditions <br /> A Low Impact Development(LID)treatment control of Bioretention Basin was utilized to meet <br /> the stormwater volume requirements. The breakdown of the Post-Project Area and the <br /> Determination of Volume is shown below on Table 2. <br /> Table 2—Determination of Post-Development(Proposed Conditions)Volume <br /> Element Weighted 0.51-inch <br /> Site Element Area Percent of Runoff Runoff Storm <br /> (ft') Total Area Coeffection Coefficient Volume, <br /> (Cr) (Cra) ft3 <br /> Disturbed Soils: 143,645 0.36 0.05 0.36 x 0.05 <br /> GroupC/D Soil =0.02 <br /> Asphalt/Concrete 217,139 0.56 0.95 0.56 x 0.95 <br /> Pavement =0.53 <br /> 08 x 1.00 <br /> Bio Basin 32,566 0.08 1.00 0. =0.08 <br /> Total 394,652 0.63 1 10,509 <br /> Total Volume <br /> Reduction 10,509- 839 <br /> Required <br /> = 9,670 <br /> 220 Norwood Park South,Suite 201 • Norwood,MA 02062 T(781)619-9500 • F(203)630-2615• www.blcompanies.com <br /> 5 <br />